Communication systems provide several options for obtaining access to broadcast video content. Consumers may receive broadcast standard definition (SD) and high definition (HD) television broadcasts from the air with an antenna. Analog and digital cable television networks distribute a variety of television stations in most communities on a subscription basis. In addition, satellite television and new internet protocol (IP) television services provide other subscription alternatives for consumers. Analog video signals may be coded in accordance with a number of video standards including NTSC, PAL and SECAM. Digital video signals may be encoded in accordance with standards such as Quicktime, (motion picture expert group) MPEG-2, MPEG-4, or H.264. In addition to digital coding, some video signals are scrambled to provide access to these signals, only to the subscribers that have paid to access the particular content.
The desire for video content has driven cellular telephone networks to begin offering video programs to their subscribers as streaming video. In this fashion, users of mobile devices may have access to video programming on the go. Some of the techniques used in providing broadcast video content to stationary devices are not suitable for adaptation to the viewing environment associated with a handheld mobile device.
Watermarking is a technique utilized to protect digital media from unauthorized use or illegal copying, such as with copyrighted material, for example. Watermarking of digital media may fall into two categories: visible or invisible. Visible watermarks are typically added to digital images to indicate ownership and to thwart unauthorized use of the images. The watermark may comprise the identity of the owner and/or a copyright symbol and date, for example. This type of watermark may be considered a spatial watermark in that the data is embedded spatially in an image, and the watermark signal is distinct from the original image data. Spatial watermarks may not be robust against attacks due to the ability of filtering, removing and/or cropping the data.
Invisible watermarks do not change the image to a perceptible extent. This may be accomplished by minor changes in the least significant bits of the original data. Watermarks that are unknown to the end user may be designated as steganographic watermarks.
A watermarking process may embed the data in the frequency domain, making it more robust against attack. The technique may be analogous to spread spectrum encoding in communications, where the data to be embedded may be spread over a multitude of frequencies by modulating the watermark signal with pseudo-noise before adding it to the original data. The low signal amplitude, due to the watermark being invisible, the large bandwidth of the original data (image or video, for example), and the shortness of the watermark message, are all factors that indicate spread spectrum encoding is a logical choice.
In addition to embedding a watermark in digital multimedia data, detecting whether a watermark is present may also be important in the protection of multimedia data. Multimedia players may include watermark sensing electronics to preclude the use of unauthorized or pirated media.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings.